Metal fusion bonding – Process – Using dynamic frictional energy
Patent
1998-09-09
2000-11-07
Ryan, Patrick
Metal fusion bonding
Process
Using dynamic frictional energy
228 11, B23K 106, B23K 520, B23K 3700, B23K 2012, B23K 3102
Patent
active
061423602
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of friction welding and in particular, a method of radial friction welding for welding two tubular members in end to end relationships.
Conventional methods of welding tubular members, such as lengths of pipe spool, together in end to end relationships have involved electric arc welding by a skilled operator. Such welding is time consuming as the weld is progressed circumferentially around the join in the tubular members. In addition, traditional welding techniques involve melting the metal of the tubulars which may not be suitable for bi-metallic tubulars and melting of the material can result in a number of metallurgical problems. In addition, it may be necessary to carry out the welding operation in an inert atmosphere to prevent or minimise oxidation of the metal of the tubular members.
Welding of tubular members in an end to end relationship has been suggested by radial friction welding. This method involves chamfering the ends of tubular members to be joined together so that when the
A V-shaped ring is placed in the V-shaped recess and rotated at high-speed while being compressed to bring it into contact with the ends of the tubular members to form a friction weld to weld the tubular members together.
However, in practice it has been found that this method of friction welding of the tubulars has a tendency for the weld to be flawed as the weld tends to bridge above the junction of the tubulars and results in a defect in the weld on the internal surface of the tubular members. This is a particular problem where the tubular members are intended to convey fluids, for example the tubular members on part of a pipeline. Because of these problems, radial friction welding of pipes has not been pursued further.
In accordance with the present invention, a method of friction welding two tubular members in an end to end relationship comprises providing the end of each tubular member to be joined with a shaped portion, the shaped portion having a surface which is substantially perpendicular to the radius of the tubular member and a second surface at an obtuse angle to the radius of the tubular member, such that when the ends to be joined are brought into contact with each other, the shaped portions define a three sided channel; locating a ring shaped member having a quadrilateral cross-section in the channel, the ring shaped member having a radius which is greater than the radius of the first surface and less than the radius of the external wall of the tubular member, rotating the ring relative to the tubular members and subsequently compressing the ring, to bring the ring into contact with the shaped portions of the tubular members to form a friction weld which welds the tubular members in an end to end relationship.
In accordance with another aspect of the present invention, a ring shaped member for friction welding to tubular members in an end to end relationship, wherein the ring shaped member has a quadrilateral cross-section.
The invention has the advantage that by having a channel with a surface which is substantially perpendicular to the radius of two tubular members and to the compression force applied to the ring, it is possible to friction weld two tubular members in an end to end relationship and minimise the possibility of defects in the friction weld.
Preferably, the ring shaped member has a substantially trapezial cross-section and the trapezial cross-section of the ring shaped member is of a generally similar shape to the cross-sectional shape of the channel formed when the shaped ends of the tubular members are brought into end to end relationships.
Typically, the ring shaped member is of the same material as the tubular members to be welded in an end to end relationship. Preferably, the tubular members and the ring shaped member are formed from a metal. Typically, where the tubular members are bi-metallic, the ring shaped member may also be bi-metallic.
Preferably, a support member is inserted into the tubular members to support the ends of the tubular members d
REFERENCES:
patent: 3874067 (1975-04-01), Toyooka et al.
patent: 4063676 (1977-12-01), Lilly
patent: 4331280 (1982-05-01), Terabayashi et al.
Fitzpatricks
Newsome Cecilia
Ryan Patrick
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